1. Field of the Invention
The present invention relates to a rotary electric machine such as a three-phase alternating current generator or a three-phase induction electric motor.
2. Description of Related Art
JP-A-4-8140 discloses a conventional rotary electric machine. In this reference, as shown in FIG. 11, a three-phase Y-form connection circuit 101 including three first windings 100, which are connected in Y-form, is combined with a three-phase delta-form connection circuit 103 including three second windings 102 which are connected in delta-form. The distribution of an air gap magnetomotive force generated on the side of a stator is made uniform with respect to the rotation of pole cores of a rotor to suppress an electromagnetic noise by providing a phase difference of about 30.degree. between voltage vectors 104 and 105 of the first and second windings 100 and 102, respectively as shown in the vector diagram of FIG. 12.
However, in the above-mentioned device, in order to provide the phase difference of about 30.degree. between the first and second windings, it is necessary to double the number of slots in the stator as compared with that of prior art devices, wherein the stator windings are connected only in Y-form or only in delta-form, preceding the above mentioned prior art. In other words, it is necessary to provide a stator core of the above mentioned device with a great many slots. As a result, the winding operation becomes complicated, and the width of each of the core teeth in the stator core is halved and hence, the core teeth may be readily deformed during the winding operation or the stator core assembling operation.